Process for producing perfluoropolyoxyalkylene peroxide compound

ABSTRACT

The present invention provides a process for producing a perfluoropolyoxyalkylene peroxide compound comprising a step of reacting a perfluoroalkene with oxygen, wherein the reaction of the perfluoroalkene with oxygen is performed in a microreactor.

TECHNICAL FIELD

The present invention relates to a process for producing aperfluoropolyoxyalkylene peroxide compound.

BACKGROUND ART

A perfluoropolyether compound is widely used as a lubricant, anintermediate of various polymers, or the like and its application hasbeen further expanded. The perfluoropolyoxyalkylene peroxide compound isknown as a raw material of the perfluoropolyether compound. Theperfluoropolyether compound can be obtained by the degradation or thereduction of the perfluoropolyoxyalkylene peroxide compound.

As a process for producing the perfluoropolyoxyalkylene peroxidecompound, for example, a method in which tetrafluoroethylene is reactedwith oxygen is known. Representatively, the reaction is performed byreacting tetrafluoroethylene with oxygen under an ultravioletirradiation (Patent Document 1). Alternatively, a method is knownwherein the reaction of tetrafluoroethylene with oxygen is started byadding a fluorine source, for example, F₂, a FO-alkyl or the likewithout the ultraviolet irradiation (Patent Document 2). These reactionshave been performed as a batch reaction by using a reactor having ageneral size (in Patent Documents 1 and 2, a grass reactor of 500 mL).

PRIOR ART DOCUMENT Patent Document

Patent Document 1: Japanese Laid-Open Patent Publication No. 6-128373

Patent Document 2: Japanese Laid-Open Patent Publication No. 4-505171

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

As the application of the perfluoropolyether compound is expanded, ademand to provide perfluoropolyether compounds having various variationsof a molecular weight or a backbone structure is increased. That is,also as to the perfluoropolyoxyalkylene peroxide compound which is a rawmaterial of the perfluoropolyether compound, a method is required whichis able to produce perfluoropolyoxyalkylene peroxide compounds havingvarious variations of a molecular weight or a backbone structure.However, it is difficult to obtain the perfluoropolyoxyalkylene peroxidehaving various variations of a molecular weight or a backbone structureby using the methods of Patent Documents 1 and 2.

Furthermore, in the batch reaction described above, ahydrochlorofluorocarbon (HCFC) solvent or a chlorofluorocarbon (CFC)solvent is used as a solvent in order to prevent the precipitation of apolymer produced in the reaction. However, the HCFC solvent or the CFCsolvent is an ozone-depleting substance and a greenhouse effect gas,therefore, these use is not preferable.

An object of the present invention is to provide a process for producingwhich is able to efficiently obtain the perfluoropolyoxyalkyleneperoxide compound having a specific physical property or a process forproducing which is able to be performed without using the HCFC solventor the CFC solvent.

Means to Solve the Problem

As a result of intensively studying, the inventors of the presentinvention have found that by performing the reaction of theperfluoroalkene with oxygen in the microreactor, it becomes possible tosuccessfully perform the reaction without using the HCFC solvent or theCFC solvent and obtain the perfluoropolyoxyalkylene peroxide compoundhaving a specific physical property, and have reached the presentinvention.

According to an aspect of the present invention, there is provided aprocess for producing a perfluoropolyoxyalkylene peroxide compoundcomprising a step of reacting a perfluoroalkene with oxygen, wherein thereaction of the perfluoroalkene with oxygen is performed in amicroreactor.

One embodiment is the process for producing described above furthercomprising a step of introducing a fluorine source into a reactionmixture containing the perfluoroalkene and oxygen.

Another embodiment is the process for producing described above furthercomprising a step of light-irradiating a reaction mixture of theperfluoroalkene and oxygen.

Another embodiment is the process for producing described above furthercomprising a step of introducing a fluorine source into a reactionmixture of the perfluoroalkene and oxygen and light-irradiating thereaction mixture.

Effect of the Invention

According to the present invention, by performing the reaction of theperfluoroalkene with oxygen in the microreactor, theperfluoropolyoxyalkylene peroxide compound having a specific physicalproperty can be obtained without using the HCFC solvent or the CFCsolvent.

EMBODIMENTS TO CARRY OUT THE INVENTION

Hereinafter, the process for producing of the present invention will bedescribed.

The term “perfluoroalkene” as used herein represents a compound whereinall of hydrogen atoms of an alkene are substituted with a fluorine atom.

The term “alkene” described above represents a straight or branchedunsaturated hydrocarbon having one double bond.

With respect to the perfluoroalkene, the number of carbon in the alkenechain is preferably 2 to 12, preferably 2 to 8, more preferably 2 to 6,particularly preferably 2.

The perfluoroalkene used in the present invention is preferablystraight. The perfluoroalkene used in the present invention ispreferably a compound having the double bond at the molecular terminalof the following formula:R¹—CF═CF₂wherein R¹ is a fluorine atom or a perfluoroalkyl group having 1 to 11carbon atoms.

R¹ may be preferably a fluorine atom or a perfluoroalkyl group having 1to 5 carbon atoms, for example trifluoromethyl, pentafluoroethyl,heptafluoro-n-propyl, nonafluoro-n-butyl, undecafluoro-n-pentyl, morepreferably a fluorine atom.

The perfluoroalkene as used herein is preferably tetrafluoroethylene orhexafluoropropene, more preferably tetrafluoroethylene.

The perfluoroalkene may further have a substituent. Examples of thesubstituent include, but are not particularly limited to, for exampleone or more groups selected from a halogen atom (for example, a fluorineatom, a chlorine atom, a bromine atom, or the like); and a C₁₋₆ alkylgroup, a C₂₋₆ alkenyl group, a C₂₋₆ alkynyl group, a C₃₋₁₀ cycloalkylgroup, a C₃₋₁₀ unsaturated cycloalkyl group, a 5-10 memberedheterocyclyl group, a 5-10 membered unsaturated heterocyclyl group, aC₆₋₁₀ aryl group, and a 5-10 membered heteroaryl group, which may besubstituted by one or more halogen atoms.

In a preferable embodiment, the perfluoroalkene described above does nothave the above substituent.

The perfluoropolyoxyalkylene peroxide compound produced by the processfor producing of the present invention is a compound having a peroxidestructure (—O—O—) and a perfluoropolyether structure(—(C_(n)F_(2n)O)_(m)—) in its molecular. In —(C_(n)F_(2n)O)_(m)—described above, n is an integer independently selected in therespective units in parentheses with the subscript m, for example aninteger of to 12, preferably an integer of 1 to 4, and m is an arbitraryinteger, preferably an integer of 2 to 2,000, for example, an integer of20 to 2,000.

In a preferably embodiment, the perfluoropolyoxyalkylene peroxidecompound is a compound of the following formula (I).Rf-[(OC₄F₈)_(a)—(OC₃F₆)_(b)—(OC₂F₄)_(c)—(OCF₂)_(d)—(O)_(e)]—Rf′  (I)

In the above formula, Rf and Rf′ are each independently —CF₃, —CF₂CF₃,—COF or —CF₂COF.

In the above formula, a and b may be each independently an integer of 0to 100, for example an integer of 1 to 100, preferably an integer of 0to 50, more preferably an integer of 0 to 30. In the above formula, cand d may be each independently an integer of 0 to 1,000, for example aninteger of 2 to 1,000, preferably an integer of 0 to 800, morepreferably an integer of 2 to 600, for example, an integer of 10 to 600.The sum of a, b, c and d may be an integer 2 to 2,000, preferably aninteger of 2 to 1,500, more preferably an integer of 2 to 1,000, forexample an integer of 100 to 800 or an integer of 250 to 800. In theabove formula, e may be an integer of 0 to 250, for example an integerof 1 or more or 5 or more and 250 or less, preferably an integer of 0 to150, more preferably an integer of 0 to 100, for example 50 or less, 40or less or 35 or less.

The occurrence order of the respective repeating units in parentheseswith the subscript a, b, c, d or e is not limited in the formula. Amongthese repeating units, the —(OC₄F₈)— group may be any of—(OCF₂CF₂CF₂CF₂)—, —(OCF(CF₃) CF₂CF₂)—, —(OCF₂CF(CF₃)CF₂)—,—(OCF₂CF₂CF(CF₃))—, —(OC(CF₃)₂CF₂)—, —(OCF₂C(CF₃)₂)—,—(OCF(CF₃)CF(CF₃))—, —(OCF(C₂F₅)CF₂)— and —(OCF₂CF(C₂F₅)), preferably—(OCF₂CF₂CF₂CF₂)—. The —(OC₃F₆)— group may be any of —(OCF₂CF₂CF₂)—,—(OCF(CF₃) CF₂)— and —(OCF₂CF(CF₃))—, preferably —(OCF₂CF₂CF₂)—. The—(OC₂F₄)— group may be any of —(OCF₂CF₂)— and —(OCF(CF₃))—, preferably—(OCF₂CF₂)—.

In one embodiment, the perfluoropolyoxyalkylene peroxide compound may bea compound of the following formula.Rf—[(OC₂F₄)_(c)—(OCF₂)_(d)—(O)_(e)]—Rf′

In one embodiment, a number average molecular weight of theperfluoropolyoxyalkylene peroxide compound is, for example, 5,000 ormore, preferably 10,000 or more, more preferably 15,000 or more, furtherpreferably 20,000 or more, further more preferably 25,000 or more. Anupper limit of the number average molecular weight of theperfluoropolyoxyalkylene peroxide compound is not particularly limited.For example, the number average molecular weight of theperfluoropolyoxyalkylene peroxide compound may be 150,000 or less,100,000 or less or 50,000 or less.

In the present invention, the number average molecular weight of theperfluoropolyoxyalkylene peroxide compound is measured by a GPC (Gelpermeation chromatography) analysis unless indicated otherwise.

In one embodiment, a ratio of c to d (hereinafter, referred to as a “c/dratio” or an “EM ratio”) is 0.1 or more and 5.0 or less, preferably 0.3or more and 4.0 or less, more preferably 0.5 or more and 3.0 or less,preferably 2.0 or less or 1.2 or less, for example 0.7 or more and 2.0or less or 0.8 or more and 1.2 or less.

In the present invention, the EM ratio is measured by a ¹⁹F-NMRanalysis.

In one embodiment, a PO value of the perfluoropolyoxyalkylene peroxidecompound is 8.6 or less, preferably 7.0 or less. A lower limit of the POvalue is, preferably 1.0 or more, more preferably 3.0 or more. The POvalue represents a mass of a reactive oxygen (one oxygen of oxygensforming —O—O—) contained in 100 g of a compound.

In the present invention, the PO value is measured by a ¹⁹F-NMRanalysis.

In a preferable embodiment, the perfluoropolyoxyalkylene peroxidecompound meets at least two, preferably all of following requirements(a) to (c):

(a) the number average molecular weight is 5,000 or more, preferably15,000 or more,

(b) the EM ratio is 0.1 to 5.0, preferably 0.7 to 2.0, and

(c) the PO value is 8.6 or less, preferably 7.0 or less.

When the above requirements (a) and/or (c) are met, a molecular weightof the perfluoropolyether compound obtained by the degradation or thereduction of the perfluoropolyoxyalkylene peroxide compound can becomehigher. When the above requirement (b) is met, the perfluoropolyethercompound having the similar EM ratio to that of theperfluoropolyoxyalkylene peroxide compound can be obtained. By using theperfluoropolyether compound having higher number average molecularweight and the EM ratio of 0.1 to 5.0, preferably 0.5 to 3.0, morepreferably 0.7 to 2.0, for example, a perfluoropolyethergroup-containing silane compound providing excellent effect as a waterand oil repellent can be obtained.

In the process for producing of the present invention, the reaction ofthe perfluoroalkene with oxygen is performed in a microreactor.

The microreactor as used herein represents a reactor having a channelwidth which does not completely separate reaction liquids and does notgenerate an interface between the liquids.

The channel width of the microreactor may be preferably 10 mm or less,more preferably 1 μm or more and 8.0 mm or less, further preferably 10μm or more and 6.0 mm or less, further more preferably 100 μm or moreand 5.0 mm or less, for example 4.9 mm or less, 4.8 mm or less, 4.5 mmor less, 4.0 mm or less or 3.0 mm or less. By making the channel widthlarger, throughput can be increased. By making the channel widthsmaller, the molecular contact (in other words, microscopic mixing) ofthe perfluoroalkene with oxygen can be sufficiently attained, as aresult of which the reaction is allowed to rapidly proceed and thereaction time (or residence time) can be shortened. In addition,effective heat removal and strict temperature control become possible.Furthermore, by making the channel width smaller, rapid reaction ordegradation of reactants (for example, tetrafluoroethylene) in thereactor can be suppressed, and even if the rapid reaction or degradationoccurs, the effects can be minimized. It is noted that the channel widthrepresents a smallest distance between opposing walls of the channel.When light irradiation is performed, since reaction effectivity can beincreased by making the channel width in a direction of the lightirradiation larger, the channel width in a direction of the lightirradiation is not limited.

The perfluoroalkene introduced into the microreactor may be in a stateof gas or liquid, and the state is appropriately selected depending onthe perfluoroalkene used and reaction conditions such as temperature,pressure, or the like. In one embodiment, the perfluoroalkene introducedinto the microreactor is in a state of gas. In another embodiment, theperfluoroalkene introduced into the microreactor is dissolved in afollowing solvent.

A flow rate of the perfluoroalkene may be preferably 0.01 to 100 mL/min,more preferably 0.1 to 10 mL/min calculated in term of a state atambient temperature (25° C.) and under ambient pressure (1 atom).

An oxygen source introduced into the microreactor is preferably anoxygen gas (O₂).

The oxygen gas to be supplied may be supplied to the reaction system asonly an oxygen gas, as a mixture of oxygen and other inert gasses suchas a nitrogen gas, or as air.

A flow rate of the oxygen may be preferably 0.01 to 200 mL/min, morepreferably 1.0 to 20 mL/min in term of a state at ambient temperature(25° C.) and under ambient pressure (1 atom).

A volume ratio of the oxygen to the perfluoroalkene to be introducedinto the microreactor (an oxygen/perfluoroalkene ratio) may be, but notparticularly limited to, for example, 0.1 to 20, preferably 0.1 to 10,more preferably 0.4 to 10, further preferably 1.0 to 8.0.

The reaction of the perfluoroalkene with the oxygen is preferablyperformed in a solvent. By performing the reaction in the solvent, apolymerization between the perfluoroalkenes and a precipitation of anobtained polymer can be suppressed.

The solvent is not limited as long as the perfluoroalkene can bedissolved in the solvent. Examples of the solvent include, for example,a perfluorocarbon (PFC) solvent such as perfluorohexane. A preferablesolvent is perfluorohexane. In the process for producing of the presentinvention, since the reaction is performed in the microreactor, thereaction can be performed without using the HCFC solvent (for example,chlorodifluoromethane (R22)) or the CFC solvent.

The solvent and the perfluoroalkene may be mixed and then, introducedinto the microreactor in a state of a mixture or a solution.Alternatively the solvent and the perfluoroalkene may be introduced intothe microreactor respectively and mixed or dissolved in themicroreactor.

A flow rate of the solvent is preferably 0.01 to 100 mL/min, morepreferably 0.1 to 10 mL/min.

A temperature in the microreactor is not limited as long as the reactionof the perfluoroalkene with oxygen can proceed, and may be, for example,−100 to 30° C., preferably −80 to 0° C.

A pressure in the microreactor is not limited as long as the reaction ofthe perfluoroalkene with oxygen can proceed, and may be, for example,0.1 to 1.0 MPa, preferably 0.1 to 0.5 MPa.

A reaction time (or a residence time) in the microreactor may be, forexample, 0.1 second to 1 hour, preferably 0.1 second to 30 minutes, forexample, 0.1 second to 30 minutes.

The reaction of the perfluoroalkene with oxygen may be started orfacilitated by performing any one of following three operations (i) to(iii):

(i) introducing the fluorine source into the reaction mixture;

(ii) light-irradiating the reaction mixture; or

(iii) introducing the fluorine source into and light-irradiating thereaction mixture.

By performing the reaction as described above, with the respect to theobtained perfluoropolyoxyalkylene peroxide compound, it becomes possibleto make the number average molecular weight higher, make the EM ratiolower, or make the PO value lower. For example, theperfluoropolyoxyalkylene peroxide compound having 5,000 or more of thenumber average molecular weight, 0.1 to 5.0 of the EM ratio, and/or 8.6or less of the PO value.

Hereinafter, the operations (i) to (iii) described above will bedescribed in more detail.

Operation (i)

The introducing of the fluorine source may be performed by adding thefluorine source to the reaction mixture of the perfluoroalkene andoxygen, or by mixing one of the perfluoroalkene and oxygen with thefluorine source before the introducing. In one embodiment, theintroducing of the fluorine source is performed by adding the fluorinesource to the reaction mixture.

The present invention is not bounded by any theory, although it isconsidered that by introducing the fluorine source, the perfluoroalkeneis reacted with fluorine, and a double bond of the perfluoroalkene iscleaved to generate a perfluoroalkyl radical. It is considered that thisradical is reacted with oxygen, as a result of which the reactionproceeds. Since this starting reaction proceeds at a relatively rapidrate, the introducing of the fluorine source increases the reaction rateof the perfluoroalkene with oxygen. In addition, it becomes possible tomake the PO value of the perfluoropolyoxyalkylene peroxide compoundlower.

Examples of the fluorine source described above include F₂ or R¹¹—OF(wherein R¹¹ is a perfluoroalkyl group having 1 to 6 carbons.). Thefluorine source is preferably F₂ gas.

The fluorine source may be introduced into the microreactor directly, ormay be introduced in a state of a mixture of the fluorine source withother materials, for example, nitrogen gas. When the fluorine source ismixed with the other materials, a concentration of the fluorine sourcemay be, but are not particularly limited to, for example, 1 to 50% byvolume, preferably 10 to 30% by volume.

An amount used of fluorine (an amount of fluorine present in thereaction system) with respect to the perfluoroalkene may be preferably0.001 to 1 mole, more preferably 0.005 to 0.1 mole, for example 0.01 to0.1 mole with respect to 1 mole of the perfluoroalkene.

A flow rate of the fluorine source may be preferably 0.001 to 5 mL/min,more preferably 0.005 to 0.5 mL/min, further preferably 0.005 to 0.1mL/min, for example 0.01 to 0.05 mL/min calculated in term of an alonestate of the fluorine source at ambient temperature (25° C.) and underambient pressure (1 atom).

When fluorine is used, the reaction time (or the residence time) in themicroreactor may be, for example, 0.1 second to 10 minutes, preferably0.5 seconds to 1 minute, for example, 1 second to 10 seconds.

Operation (ii)

The light irradiation is performed such that a subject to be irradiatedis a mixture contained in the microreactor. Therefore, when the lightirradiation is performed, a material constituting the microreactor maybe a material which a light having a prescribed wavelength penetrates,for example, a glass.

The present invention is not bound by any theory, although it isconsidered that by performing the light-irradiation, the perfluoroalkeneis reacted with oxygen to generate a biradical, as a result of which thereaction is started. In addition, by performing the light-irradiation, a—O—O— bonding in a molecular chain of a molecular whose reaction isstopped is cleaved to generate a radical again, and an extensionreaction proceeds. As a result, the molecular having a higher molecularweight can be obtained.

The light to be used is a light having preferably a wavelength of 200 nmto 350 nm, more preferably a wavelength of 220 nm to 280 nm. By theirradiation is performed by using the light having such wavelength, thereaction becomes effective.

Examples of the light source having the wavelength described aboveinclude, for example, a mercury lamp, a xenon lamp, a LED lamp, anexcimer lamp, a lamp of an electron beam or the like. The mercury lampmay be a low pressure mercury lamp, a medium mercury lamp, or a highpressure mercury lamp.

A density of the light irradiation may be preferably 0.01 W/m² to 500W/m², more preferably 0.01 W/m² to 300 W/m² on the surface of thereaction site. By making the density of irradiation of the light havingthe wavelength of 220 nm to 280 nm higher, the reaction rate can becontrolled. That is, the EM ratio and the PO value can be controlled.

In one embodiment, the wavelength of the light to be used is 220 nm to280 nm, the density of the light irradiation is 80 W/m² to 300 W/m², thereaction temperature is −100 to 25° C., and the residence time is 0.1second to 60 minutes.

In one embodiment, the reaction temperature can be changed depending onthe location. For example, the temperature is higher in an early phaseof the reaction, and then the temperature may be lowered. For example,the reaction temperature can be relatively higher (for example, −30 to30° C., preferably, −30 to 10° C.) in an early phase of the reaction(for example, for 1 to 5 minutes after starting the reaction), and thenthe temperature can be relatively lower (for example, −100 to 0° C.,preferably −80° C. to −20° C.). As such described, by setting thetemperature in the early phase of the reaction to higher, and thenlowering the temperature, the effectiveness of the reaction can beincreased. On the other hand, the temperature may be lowered in theearly phase of the reaction, and then the temperature may be raised.

When the light irradiation is performed, the reaction time (or theresidence time) in the microreactor may be, for example, 10 seconds to 1hour, preferably 30 seconds to 30 minutes, for example 1 to 30 minutes.

Operation (iii)

The addition of the fluorine source is performed similarly to Operation(i) described above, and the light irradiation is performed similarly toOperation (ii) described above. That is, Operation (iii) is acombination of the Operation (i) and Operation (ii). By combiningOperation (i) and Operation (ii), the reaction rate of theperfluoroalkene with oxygen is increased, and a perfluoropolyoxyalkyleneperoxide compound having a relatively lower PO value and a relativelyhigher molecular weight can be obtained.

As described above, the perfluoropolyoxyalkylene peroxide compound isproduced. The process for producing the perfluoropolyoxyalkyleneperoxide compound can be performed in a form of a continuous type.

EXAMPLES Examples 1 and 2

As the microreactor, a reactor was used wherein a channel of stainlesswhich has a channel width of 2 mm, a channel depth of 5 mm, a length of652.8 mm, was a ditched groove which was folded per 41 mm, and wascovered and sealed with a silica glass. An inlet port of themicroreactor was connected to a tetrafluoroethylene (TFE) tank, anoxygen (O₂) tank, and a perfluorohexane (PFH) tank via a precoolingsection, respectively.

From each raw material tank, TFE (1 mL/min), oxygen (6 mL/min), and PFH(0.24 mL/min) were supplied to a fine tube and were cooled to −45° C.(Example 1) or −60° C. (Example 2) in the precooling section, and weresupplied to the microreactor. The microreactor was irradiated with alight having the wavelength of 220 nm to 280 nm at the light irradiationdensity of 200 W/m² using a high pressure mercury lamp as a lightsource.

Evaluation

The obtained products were evaluated as follows, and a yield, a numberaverage molecular weight, an EM ratio, a PO value were calculated. Theresults are shown in the following table.

Yield

From the result of a ¹⁹F-NMR analysis, a fluorine amount incorporatedinto the polymer in the product and a fluorine amount in TFE weredetermined, and the yield was calculated according to the followingequation:Yield=(Fluorine amount incorporated into the peroxide polymer in theproduction)/(Fluorine amount in TFE)×100(%)

Number Average Molecular Weight From the result of the ¹⁹F-NMR analysis,a ratio of the number of units of CF₂CF₂OO, CF₂CF₂O, CF₂OO and CF₂O, andterminal CF₃ in a main chain of the peroxide polymer in the product wasdetermined, and the number average molecular weight (Mn) was calculatedaccording to the following equations:The number of each unit in the main chain of the polymer per onemolecular of the polymer=Ratio of each unit/((Ratio of terminal CF₃)/2)Number average molecular weight (Mn)={Molecular weight of the main chain}+{(Molecular weight of the terminalCF₃)×2}={(The number of unit CF₂CF₂OO×132)+(The number of unitCF₂CF₂O×116)+(The number of unit CF₂OO×82)+(The number of unitCF₂O×66)}+{2×69}

EM Ratio

From the result of the ¹⁹F-NMR analysis, the number of unit CF₂CF₂ andthe number of unit CF₂ in the product were determined, and the EM ratiowas calculated according to the following equation:EM ratio=(The number of unit CF₂CF₂)/(The number of unit CF₂)

PO Value

From the result of the ¹⁹F-NMR analysis, the number of unit CF₂CF₂OO andthe number of unit CF₂OO in the product were determined, a molecularweight of a reactive oxygen and a molecular weight of the polymer in theproduct were calculated, and the PO ratio was calculated according tothe following equations:Molecular weight of the reactive oxygen=(The number of unitCF₂CF₂OO×16)+(The number of unit CF₂OO×16)Molecular weight of polymer as a whole=(The number of unitCF₂CF₂OO×132)+(The number of unit CF₂CF₂O×116)+(The number of unitCF₂OO×82)+(The number of unit CF₂O×66)+(The number of unit CF₃×69)PO value=(Molecular weight of the reactive oxygen)/(Molecular weight ofpolymer as a whole)

TABLE 1 Experiment condition TFE O₂ PFH Temp. (mL/min) (mL/min) (mL/min)(° C.) Example 1 1 6 0.24 −45 Example 2 1 6 0.24 −60 Result PO value EMratio Yield (%) Mn Example 1 8.6 1.00 22 19,936 Example 2 7.5 1.51 3718,512

Examples 3 and 4

Reactions were performed similarly to Examples 1 and 2, respectively,except that a fluorine (15% of F₂ in N₂) tank was further connected tothe microreactor. The evaluation was performed similarly to Examples 0.1and 2 to determine the yield, the EM ratio, and the PO value. The numberaverage molecular weight was measured by using a GPC (gel permeationchromatography) analysis. The results are shown in the following table.

TABLE 2 Experiment condition TFE O₂ F₂ PFH Temp. (mL/min) (mL/min)(mL/min) (mL/min) (° C.) Example 3 1 6 0.11 0.24 −45 Example 4 1 6 0.110.24 −60 Result PO value EM ratio Yield (%) Mn Example 3 6.7 0.84 276,068 Example 4 7.3 1.28 34 7,513

Examples 5 and 6

Reactions were performed similarly to Examples 3 and 4, respectively,except that the light irradiation was not performed. The evaluation wasperformed similarly to Examples 1 and 2 to determine the yield, thenumber average molecular weight, the EM ratio, and the PO value. Theresults are shown in the following table.

TABLE 3 Experiment condition TFE O₂ F₂ PFH Temp. (mL/min) (mL/min)(mL/min) (mL/min) (° C.) Example 5 1 6 0.11 0.24 −45 Example 6 1 6 0.110.24 −60 Result PO value EM ratio Yield (%) Mn Example 5 4.3 0.44 6.41,495 Example 6 6.9 0.85 5.1 2,783

As seen from the above results, it was confirmed that by performing thereaction of the perfluoroalkene with oxygen in the microreactor, even ifthe perfluorocarbon solvent was used, the reaction successfullyproceeded. It was confirmed that by adding fluorine to the reactionmixture, the PO value and the EM ratio of the perfluoropolyoxyalkyleneperoxide compound could be lowered. It was confirmed that by irradiatingthe reaction mixture with the light, the perfluoropolyoxyalkyleneperoxide compound having a higher molecular weight could be obtained. Itis confirmed that by adding fluorine to the reaction mixture andirradiating the reaction mixture with the light, theperfluoropolyoxyalkylene peroxide compound having a relatively highermolecular weight, a relatively lower PO value and EM ratio could beobtained.

The present invention includes following embodiments:

Embodiment 1

A process for producing a perfluoropolyoxyalkylene peroxide compoundcomprising a step of reacting a perfluoroalkene with oxygen, wherein thereaction of the perfluoroalkene with oxygen is performed in amicroreactor.

Embodiment 2

The process for producing according to Embodiment 1, further comprisinga step of introducing a fluorine source into a reaction mixturecontaining the perfluoroalkene and oxygen.

Embodiment 3

The process for producing according to Embodiment 2, wherein thefluorine source is F₂.

Embodiment 4

The process for producing according to Embodiment 1, further comprisinga step of light irradiating a reaction mixture of the perfluoroalkeneand oxygen.

Embodiment 5

The process for producing according to Embodiment 4, wherein the lightirradiation is performed by irradiating the reaction mixture with alight having a wavelength of 200 nm to 350 nm.

Embodiment 6

The process for producing according to Embodiment 1, further comprisinga step of introducing a fluorine source into a reaction mixture of theperfluoroalkene and oxygen and light irradiating the reaction mixture.

Embodiment 7

The process for producing according to Embodiment 6, wherein thefluorine source is F₂, and the light irradiation is performed byirradiating the reaction mixture with a light having a wavelength of 200nm to 350 nm.

Embodiment 8

The process for producing according to any one of Embodiments 1-7,wherein the perfluoroalkene is tetrafluoroethylene.

Embodiment 9

The process for producing according to any one of Embodiments 1-8,wherein the perfluoropolyoxyalkylene peroxide compound is a compound ofthe formula (I):Rf—[(OC₄F₈)_(a)—(OC₃F₆)_(b)—(OC₂F₄)_(c)—(OCF₂)_(d)—(O)_(e)]—Rf′  (I)wherein:

Rf and Rf′ are each independently —CF₃, —CF₂CF₃, —COF or —CF₂COF,

a and b are each independently an integer of 0 to 100,

c and d are each independently an integer of 2 to 1,000,

the sum of a, b, c and d is a integer of 2 to 2,000,

e is an integer of 0 to 250, and

the occurrence order of the respective repeating units in parentheseswith the subscript a, b, c, d or e is not limited in the formula.

Embodiment 10

The process for producing according to Embodiment 9, wherein a c/d ratioof the perfluoropolyoxyalkylene peroxide compound is 5.0 or less.

Embodiment 11

The process for producing according to any one of Embodiments 1-10,wherein a PO value of the perfluoropolyoxyalkylene peroxide compound is8.6 or less.

Embodiment 12

The process for producing according to any one of Embodiments 1-11,wherein a number average molecular weight of theperfluoropolyoxyalkylene peroxide compound is 5,000 or more.

Embodiment 13

The process for producing according to any one of Embodiments 1-12,wherein a channel width of the microreactor is 10 mm or less.

Embodiment 14

The process for producing according to any one of Embodiments 1-13,wherein a channel width of the microreactor is 5.0 mm or less.

INDUSTRIAL APPLICABILITY

According to the present invention, the perfluoropolyoxyalkyleneperoxide compound can be suitably produced.

The invention claimed is:
 1. A process for producing aperfluoropolyoxyalkylene peroxide compound comprising a step of reactinga perfluoroalkene with oxygen, wherein the reaction of theperfluoroalkene with oxygen is performed at −100° C. to 30° C. in amicroreactor.
 2. The process for producing according to claim 1, furthercomprising a step of introducing a fluorine source into a reactionmixture containing the perfluoroalkene and oxygen.
 3. The process forproducing according to claim 2, wherein the fluorine source is F₂. 4.The process for producing according to claim 1, further comprising astep of light irradiating a reaction mixture of the perfluoroalkene andoxygen.
 5. The process for producing according to claim 4, wherein thelight irradiation is performed by irradiating the reaction mixture witha light having a wavelength of 200 nm to 350 nm.
 6. The process forproducing according to claim 1, further comprising a step of introducinga fluorine source into a reaction mixture of the perfluoroalkene andoxygen and light irradiating the reaction mixture.
 7. The process forproducing according to claim 6, wherein the fluorine source is F₂, andthe light irradiation is performed by irradiating the reaction mixturewith a light having a wavelength of 200 nm to 350 nm.
 8. The process forproducing according to claim 1, wherein the perfluoroalkene istetrafluoroethylene.
 9. The process for producing according to claim 1,wherein the perfluoropolyoxyalkylene peroxide compound is a compound ofthe formula (I):Rf-[(OC₄F₈)_(a)—(OC₃F₆)_(b)—(OC₂F₄)_(c)—(OCF₂)_(d)—(O)_(e)]—Rf′  (I)wherein: Rf and Rf′ are each independently —CF₃, —CF₂CF₃, —COF or—CF₂COF, a and b are each independently an integer of 0 to 100, c and dare each independently an integer of 2 to 1,000, the sum of a, b, c andd is a integer of 2 to 2,000, e is an integer of 0 to 250, and theoccurrence order of the respective repeating units in parentheses withthe subscript a, b, c, d or e is not limited in the formula.
 10. Theprocess for producing according to claim 1, wherein the perfluoroalkeneis tetrafluoroethylene, and the perfluoropolyoxyalkylene peroxidecompound is a compound of the formula (I):Rf-[(OC₄F₈)_(a)—(OC₃F₆)_(b)—(OC₂F₄)_(c)—(OCF₂)_(d)—(O)_(e)]—Rf′  (I)wherein: Rf and Rf′ are each independently —CF₃, —CF₂CF₃, —COF or—CF₂COF, a and b are each independently an integer of 0 to 100, c and dare each independently an integer of 2 to 1,000, the sum of a, b, c andd is a integer of 2 to 2,000, e is an integer of 0 to 250, and theoccurrence order of the respective repeating units in parentheses withthe subscript a, b, c, d or e is not limited in the formula.
 11. Theprocess for producing according to claim 9, wherein a c/d ratio of theperfluoropolyoxyalkylene peroxide compound is 5.0 or less.
 12. Theprocess for producing according to claim 1, wherein a PO value of theperfluoropolyoxyalkylene peroxide compound is 8.6 or less.
 13. Theprocess for producing according to claim 1, wherein a number averagemolecular weight of the perfluoropolyoxyalkylene peroxide compound is5,000 or more.
 14. The process for producing according to claim 1,wherein a channel width of the microreactor is 10 mm or less.
 15. Theprocess for producing according to claim 1, wherein a channel width ofthe microreactor is 5.0 mm or less.